This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Small animal X-ray computed tomography (microCT) is an economical and highly quantitative three-dimensional method for visualizing blood vessels and angiogenesis preclinically, even in comparison to small animal magnetic resonance imaging. In this collaboration, we are developing practical guidelines for rapid, accurate visualization of intermediate to large caliber (greater than 93 micron) blood vessels for serial assessment of vascularity during preclinical therapeutic trials in living mice. Because of the long scan times for most small animal computed tomography instruments, we are using a long-acting blood pool contrast agent. In addition to guidelines, we are also further developing tools to assess vessels through qualitative visual renderings. The same optimized acquisition settings will be necessary for segmentation analysis and will allow quantitative analysis of tumor blood volume, vessel density, vessel caliber, degree of branching, and tortuosity.